The present invention relates to a wheel and brake device for a means of transportation, preferably a transport trolley, where at least one wheel is pivotally supported and where the brake device includes at least one brake activating means at the front and/or rear end of the means of transportation, the activating means being activatable and deactivatable by activating in one direction only, a cam mechanism defining two fixed resting positions for an activated brake and for a deactivated brake, respectively, and at least one brake lever connecting the brake activating means to a brake block intended for engagement with teeth on at least one wheel.
Such devices are known from various means of transportation, especially transport trolleys used in aircraft cabins. In such transportation trolleys at least the pairs of wheels at one end of the trolley are pivotally supported for the sake of trolley manoeuvrability. Such trolleys are provided with a brake device which should be able to brake the wheels even when the trolleys are heavily loaded and when the floor in the aircraft cabin is sloping, e.g., during take-off. Normally, the brake is activated by means of foot pedals located at each end of the trolley and which enables the establishment of an engagement between the brake block and the wheels.
U.S. Pat. No. 3,571,842 discloses a brake device of the type mentioned above. However, this device is associated with the disadvantage that the brake and the brake activating means are directly connected to a wheel. If the wheel can pivot, it becomes difficult to operate the brake activating means as in certain circumstances it may have moved underneath the means of transportation. Furthermore, its use is very troublesome as a brake activating means is required for each wheel to be braked. According to this patent, a friction engagement is established between the brake block and the wheel. This is disadvantageous as wear of the friction surfaces of the wheels and the brake block neccesitate a relatively frequent inspection and adjustment. This problem is solved by a brake device according to DE-A-3,130,100 wherein a mechanical engagement between the brake block and the teeth on the wheel of the trolley is illustrated. However, this device is complicated and demands a precise adjustment of the engagement portion of the brake block and the teeth.
Transportation trolleys are also known which at one and/or other end have a brake activating means acting on several wheels However, the brake device on the known trolleys is complex as, at each end, they comprise two foot pedals which by a downwardly orientated pressure both activate and deactivate the brake. Alternatively, one brake pedal only may be provided at each end which is activated and deactivated by a downwardly orientated pressure and an upwardly orientated pressure, respectively. However, this construction would be harmful to the shoes of the staff when they apply the upwardly directed pressure with the upper side of their shoe. In the known trolleys, an activating and a deactivating operation of the brake is effected from one end of the trolley. If a deactivation has to be effected from the opposite end of the trolley to the end where the activation is effected, a complex construction with doubling of several elements is required.
Even though the drawbacks associated with the known trolleys of the type mentioned above is explained with a view to transportation trolleys utilized in aircraft cabins, it is obvious that other means of transportation of a similar type as, e.g., fodder trucks for use in stables, waste containers, hospital beds, etc., suffer from the same or corresponding drawbacks. Therefore, the invention may advantageously be used in connection with various means of transportation.
It is the object of the present invention to remedy the above-mentioned drawbacks and to provide a device of the type mentioned in the preamble of the specification which is easy to operate and which requires little maintenance and adjustment and which also permits safe braking.